heterogeneous quantization for different backends

[goka-wu]

My team aims to develop a heterogeneous inference framework using ExecuTorch, but we are currently grappling with challenges in heterogeneous quantization.

Consider this scenario: For a single model, we plan to simultaneously delegate computations to NPU-A, NPU-B, and CPU backends. The CPU will utilize XNNPACKQuantizer, while NPU-A and NPU-B require custom quantization algorithms. How can we apply these three distinct quantization methods to their respective partitions before the graph is partitioned?

Based on my understanding of ExecuTorch's workflow: Quantization at Aten IR → Partitioning at EdgeIR,
if the graph is partitioned into:

P1 (executed on NPU-A)
P2 (executed on NPU-B)
P3 (executed on CPU via XNNPACK)

How can we ensure that the NPU-A-specific quantization algorithm is applied to P1 during the Aten IR quantization stage, given that partitioning occurs later at the Edge IR stage?